Refrigerating system



Jan. 25, 1944. o. ZEHNDER REFRIGERATING SYSTEM Filed July 12, 1940 P ams Jan. 25, 1944 2,340,034

UNITED STATES. PATENT omce 2,340.03! REFRIGERATING SYSTEM Otto Zehnder, Granichen, Switzerland, assignmto Gebriider Zehndcr, Badiatorendz Apparatebau, Graniclien, Switzerland Application July 12, 1940, Serial No. 345,225

Switzerland July 12, 1939 8 Claims. (Cl. 6H)

This invention relates to compression refrigbetween a conveying device and the driving moerting systems comprising piston operated comtor; pressors, the suction stroke of the compressor Fig. is a schematic view of an example of a being effected by the pressure of the refrigerant refrigerating system according to the invention vapor passing into the compressor and the comincluding a flooded evaporator, and

pression stroke of the compressor being efiected E18- 6 is a View O a modified detaiL by a source of electric power. which is auto- In the first example of efri erating system. matically connected. the condenser in which the compressed ammonia According to the invention, the suction strok vapors are condensed by withdrawing heat thereof the compressor piston is effected by refrigerm, is designated y l in i A lower nant vapor passing into the compressor wh n th duit 2 leads from the condenser I to a nozzle pressure of the refrigerant vapor present in the throttling arrransemen 3 in 111 the m of a suction conduit surpasses a certain value, in conp t r re ulatin evice With W i th closed by a thermostatic device, the piston of the F 4 are connected through conduits compressor then being actuated for performing sneetively with the upper space of a cylinder 5 its compression stroke by means of the elecguiding reflipmce-mry mpressor piston 7 m motor and at the end of the compression which moves upwardly or downwardly dependent stroke the piston influences a control memberen eertem Penditmne of eperetion- W pemts which interrupts the energizing circuit of the of er the two newts 4 v spnne motor, pressed valve discs it, it respectively, are ar- 3 this means it is ssible to 0 rate the s ranged in the head of the cylinder 5, each valve temyby an unusuauyposman gg of z disc normally closing its associated valve opening strokes The compressor cylinder is compara through the intermediary of resilient valve seats tively large and, with a relatively large evaporatrespectively of which are made of ing surface in the evaporator, the evaporator rubber er a P oviding perfect sealing pressure drop will be very little, approximating, The piston F is provided with run 8 and for tan m o. 3o liner 9 which ismade of hygroscopic material, for g: fg gz 3: Ega 5 g g gg 3:: example felt, and serve for lubricating the cy1menergy inherent in the refrigerant vapor can be Above the rim 3 as an on Winthe electric motor. Moreover provision can be fr.examp1e a special rubber material and within d. The piston i cooperates with two parduring the time elapsing between compression arrange strokes that is in the course of each succeeding anally disposed conveyer chains 10 each of whmh suction stroke which occur under the influence passes over two chain wheels the latter of the refrigerant returning to the compressor the axle 13 to which a gear wheel 53 is fixed which from the eveperemr' intermeshes with a pinion 54 which is in turn se- Exemplee of the comPreseien refrigerating cured on the rotor shaft 55 of an electric driving system aecordmi the Invention are 111mm motor I. The two conveyer chains 10 are in- Y y exemplifi d in the accompanying drawing 5 tel-connected by a transverse driving pin 14 carin which rying a roller II,

Fig 1 shows an elevation partly in sect Referring to Figs. 1 to 3, the piston 7' is asthe compressor and associated accessories of a sumed to be moved'downwardly under the mfirst example of a refrigerating system a f fluence of the pressure of the refrigerant vapor ingto the invention including an injection evapopassing {mm t evaporator 4 through conduit rator; 4 into the cylinder 8, so that the piston rod i8 Fig. 2'shows a side elevation of Fig. 1; rests against the driving pin 14 through a, r FIE. 3 is a sectional view of a detail of Fig. 2 piece ll, thereby moving said pin along with it on a larger scale; and moving the pair of chains 10 in the corre- Fig. 4 is a view of a modification-of the drive 35 sponding direction and turning the pair of wheels 4 wheels being united into a double chain wheel to v the piston 1 which 53, 54 accordingly. This has the result that during the suction stroke of the piston 1, then taking place, the conveyer chains have the tendency to drive the electric motor 44 at a higher than synchronous speed, so that a wattmeter (not shown) connected in circuit is stopped, and does not register any current consumed, although the eletcric motor 46 is not disconnected from the network 46, 4'1. The suction stroke of the piston 7 comes to an end by the crosspiece l8 arranged on the piston rod l8 hitting the chain wheel axle 13. When the piston I arrives in the respective position, the cross pin 18 provided with the roller" keeps on moving together with the pair of chains ill, thereby circulating about the chain wheel axle 13, whereupon the cross pin it moves upwardly in order to hit the crosspiece l8 and consequently move the piston I upwardly which thus performs its compression stroke.

When sufficient refrigerant has been expanded into the evaporator 4 to cause the pressure therein to rise sufficiently, an expansible tube 62 connected with the evaporator via a conduit 53 and having an arm 16 for controlling a mercury tumbler switch 40 is extended. The tumbler switch 10 which is included in the energizing circuit of the electric driving motor M by a wire loop 80 and pivoted at 11 engages by means of its carrier arm into a notch provided in the control arm 16 (Fig. 2). In consequence of the expansible tube 52 being extended the control arm 75 is moved to the left hand side with reference to the drawing, whereby the tumbler switch 50 is rocked about its pivot axis I'll into the connecting position as shown in this figure, so that the energizing circuit of the motor is closed and thus the electric motor W is driven electrically instead of mechanically as before. After the piston I has traveled through a certain length of suction stroke a bell cranklever I8 is rocked ,by the crosspiece [8' against the influence of a spring 19, so that the bell crank lever 18 displaces a control bolt 80 toward the right in the drawing by means of its shorter depending arm. The bell crank lever 18 engages in a slot which is formed in the control bolt 80 so as to allow the bell crank lever 18 to perform a rocking movement in the direction opposite to the movement described above without influencing the control bolt 80, so that this bolt remains in position without being disturbed in the course of the suction stroke of the piston 'I. In the course of the compression stroke of the piston I the control bolt 80 is however axially displaced in the guide in which it is arranged and is thus retracted from the path of rocking movement of the tumbler switch 40.

As the pressure in the evaporator 4 decreases the expansible tube 62 contracts in consequence of which the control arm having been pulled to the left with reference to the drawing tends to swing the tumbler switch 40 toward the left into disconnecting position. This rocking movement of the tumbler switch 40 into disconnecting position is, however, possible only if the control bolt 80 is retracted from its locking position by takes place at a certain time moment, namely after the piston I has passed through a predetermined length of travel in the course of the compression stroke.

As the tumbler switch 40 is rocked into disconnecting position, whereby the electric motor 44 is set at rest,.the piston 1 then being loaded imparts a driving impulse to the pair of conveyer chains I0 and thus to the electric motor 44 just sufllcient for returning the driving pin 14 into initial position which corresponds to the position of the crosspiece [8, carried by the piston rod I8, at the end of the suction stroke of the piston 1.

When the electric motor 44 is connected again, 7

pletely unloaded until the driving bolt 14 has moved round the underside of the chain wheel axle I3. The electric motor 64 is, therefore, adapted to start unloaded each time after the performance of a compression stroke the suction stroke for the reason that du:ing the suction stroke of the piston l the pair of chains 10 is driven from the piston I and during the compression stroke of the piston I from the electric motor 46. By means of the control bolt 80 which is automatically actuated by the piston I and is associated with the mercury tumbler switch included in the energizing circuit of the motor this tumbler switch is prevented from changing over at an improper time, so that disconnecting of the system is impossible, when the driving pin It hits the crosspiece IS on the piston rod IS in the course of the upward movement of this pin, in' order to adapt the piston I subsequently to perform its suction stroke.

In the arrangement of Fig. 4 it is assumed that between the wheel 54 and the motor shaft 55 a unidirectional coupling 91 is arranged to vwhich end the wheel 54 is provided with interior ratchet teeth. The coupling 91 may consist of compression stroke,

- nected in circuit with a pair of outwardly spring pressed teeth located in a transverse bore in shaft 55, and which have inclined outer faces adapted to cooperate .with correspondingly shaped teeth formed within wheel 54.

Due to the fact that tive during the suction stroke the suction period can be shortened by giving the compressor piston a lead on the motor. During the suction stroke the compressor piston travels so fast that the space in the cylinder increases faster than gas is supplied thereto. Without the presence of this coupling the piston would require an equal amount of time for effecting the suction stroke as for effecting the compression stroke. The reason for this is that by action of the pressure in the evaporator there exists a tendency to drive the motor at a highr speed than synchronism from the conveying device after the piston has reached its top dead centre in the course of the and that this tendency toward higher speed is opposed in induction motors by means of a resistance for each corresponding increase in speed. By virtue of the above-mentioned coupling the detrimental friction influences from the cylinder wall, which at low suction speeds of the piston affect the degree of efflciency to a great extent, can be considerably reduced, especially if the cylinder is in hot condition, due to the reduction in time obtained for the filling of the cylinder. The wattmeter conthe motor records the energy losses of the motor while running at noload. Due to the detrimental influence of the cylinder wall being decreased, the increase of degreeof efficiency is considerably greater than the no-load losses during a very short time period the length of which corresponds to that of the duration of the suction stroke of the piston.

In the arrangement shown in Fig. 5. a capillary tube 8| is soldered onto the evaporator 4, the liquid contained therein, which is sensitive to the motor is given time for starting comduring this coupling is inopera-' which moreover are set up only v with the first example.

heat, acts on the expansion tube 82 of a thermostatic device. The throttling device (not shown) connected with the evaporator 4 in advance thereof is constructed as a float valve by which the'supply conduit 2 can be wholly closed dependent on requirements. The expansion tube 82 cooperates with the mercury tumbler switch through a conducting wire 82 with a winding 83 which surrounds a core member 84 which is further surrounded by a winding 85. The two windings 83, 85,are connected through a connecting wire 86 with a line wire 41 of the network from the line wire 46 of which a conducting wire 81 lead to the tumbler switch 40. A conducting wire 88 leads from the her 90.

As the temperature and thus also the pressure of the refrigerant vapor in the evaporator 4 rises, as explained in connection with the first example, the piston I of cylinder 5 moves downward and the electric motor is driven by the pair of conveyer chains 10. On the other hand the stroke of the piston, as explained in connection The winding 85 is then energised and the tumbler switch 82 disconnected a fixed contact arm 89 with- 3 91 between the shaft of'the electric motor 44 and the auxiliary wheel 84. as shown in F18u4- for the same purpose the pair of endless chains moving the piston 'I along with it during the compression stroke. Otherwise the system operates on the same principle as previously explained. I

What I claim is:

for disconnecting said motor.

2. In a compression refrigerating system com 3. In a compression refrigerating system comprising pisto through said relay is closed.

5. In a compression refrigerating system comprising piston operated compression means for compressing the refrigerant, as claimed in claim connection between said endless transmitting device and said motor a unidirectional coupling is arranged which is ineflective during said suction stroke of said piston.

6. Refrigerating machine according to claim 1 and in which the endless rotating power transmitting device is provided with a plurality of driving pins for cooperation with said piston, so

OTTO ZEHNDER. 

